An exhaust hood mounting structure for pneumatic nail guns, including an exhaust hood mounted on the exhaust port of a pneumatic nail gun and having a center countersunk hole, a locating cup mounted within the center countersunk hole on the exhaust hood and having a center through hole, a screw inserted through the center through hole on the locating cup and the center countersunk hole on the exhaust hood and then threaded into a screw hole on the pneumatic nail gun within the exhaust port, wherein a corrugated spring is mounted around the screw and retained between the exhaust hood and the locating cup for permitting the exhaust hood to be turned round the screw to the desired angle by hand and retained in the adjusted position when released from hand.